Various raw materials such as crude oil are mixtures of various materials, for example, various compounds, and the raw materials may be usually used after being separated into each compound. A representative process from among chemical processes for separating the mixture is a distillation process.
For example, the mixture may pass through one or more distillation columns and be distilled, a part or all of the stream may pass through a condenser or a reboiler, and then flow back to the distillation column, and a high-purity compound may be obtained through the process. In general, a raw material including a material of three or more components may pass through two or more distillation columns and may be separated into each component. For example, a low boiling point component is first separated from the raw material at the upper part of a first distillation column, and an intermediate boiling point component and a high boiling point component may be separated from the raw material at the upper and lower parts of a second distillation column connected to the first distillation column. In this case, remixing of the intermediate boiling point component may occur in the lower part area of the first distillation column, and accordingly, additional energy may be consumed.